The Tongue of the Ocean is the name of a deep oceanic trench in the Bahamas separating the islands of Andros and New Providence. The depth of the water drops from roughly 115 feet along Andros' east offshore barrier reef to over 6,000 ft, and the drop is roughly 100 miles long.
This channel - and the Providence Channel - are the two main branches of the Great Bahama Canyon, a submerged geological feature formed by erosion during periods of lower sea level. During their early history the Tongue of the Ocean and the Providence Channels were broad, relatively shallow basins flanked by growing carbonate banks. As the Blake-Bahama platform subsided, sedimentation kept pace with subsidence on the banks, but not in the basins. Many Bahamian people believe that this trench "feeds" the surrounding water area because many species of marine life emerge from it.
Taking advantage of the deep water close to shore, the United States has operated AUTEC (Atlantic Undersea Testing and Evaluation Center) on Andros since 1965 to research anti-submarine warfare for the Western Alliance using live targets and synthetic torpedoes in a realistic environment.
Today, AUTEC employs over 400 Americans and 170 Bahamians. The 1983 bilateral lease agreement provides for the use of land sites, airspace and seabed for a payment of $10.8 million a year.
It is known to Bahamian sailors as a very dangerous place due to the common presence of military personnel and equipment from a nearby United States submarine training base, the Cuban Navy and numerous drug runners and pirates. Sailors are warned to use extreme caution in this area.